It is known to provide a plurality of tools on a punching or stamping machine so that the machine can do several different punching operations, here meaning two-tool normally metalworking operations and even stamping and embossing. For precision work it is therefore necessary to provide a separate die for each punch, making it necessary to change both of these tools when a different punch is needed.
In a standard arrangement described in German Pat. No. 2,738,344 of K. Blanz an upper punch turret and a similar lower die turret are rotatable about a common vertical axis. The two turrets, constituted as wheels or carousels, are rotationally joined so they can be turned to position an interfitting punch and die in a working station beneath an actuator and above an anvil support. The workpiece is positioned between the wheels in the station and the actuator can push the punch in the station down through the workpiece into the die.
Another arrangement is shown in German Pat. No. 2,648,447 of W. Helkotter and I. Kruse. Here both of the turrets have frustoconical surfaces and are rotated about respective axes inclined to the horizontal to position the tools carried on them in vertical juxtaposition in the punching station.
The problem with both of these arrangements is that they are quite complex. Both of the turrets must be exactly controlled and positioned with respect to each other for perfect punching. This requires extensive position-detecting systems and special servomotor-type actuating arrangements. In addition the bearings of the turrets are frequently heavily loaded during the punching operation, so that these parts must be especially rugged, or provision must be made to brace the turrets during the punching operation.